package javaapplication1;
import java.io.IOException;

import java.security.SecureRandom;

import javax.crypto.Cipher;

import javax.crypto.SecretKey;

import javax.crypto.SecretKeyFactory;

import javax.crypto.spec.DESKeySpec;

import sun.misc.BASE64Decoder;

import sun.misc.BASE64Encoder;
import java.util.*;


public class Des {

private final static String DES = "DES";


    public static void main(String[] args) throws Exception {
        Scanner reader=new Scanner(System.in);
        String data ;
        String key = "wang!@#$%";
        int flag=0;
       int chooseMode;
       do{
          
       System.out.println("请输入字符串");
       data=reader.nextLine();
       if (data.equals(""))
               data=reader.nextLine();
       System.out.println(data);
       System.out.println("请选择加密或者解密，输入1(加密)或2（解密）");
       chooseMode=reader.nextInt();
      
       if(chooseMode==1){                
            /**加密**/
         System.err.println("加密后"+encrypt(data, key));
       }
            /**解密**/
       else{ 
        System.err.println("解密后"+decrypt(data, key));
     
       }
       System.out.println("输入1结束程序 输入2继续");
           chooseMode=reader.nextInt();
           if(chooseMode==1){
           break;
           }
           //else continue;
       }while(true);
          
               }  
       
 
    /**
     * Description 根据键值进行加密
     * @param data 
     * @param key  加密键byte数组
     * @return
     * @throws Exception
     */
       public static String encrypt(String data, String key) throws Exception {
        byte[] bt = encrypt(data.getBytes(), key.getBytes());
        String strs = new BASE64Encoder().encode(bt);
       return strs;
    }
 
    /**
     * Description 根据键值进行解密
     * @param data
     * @param key  加密键byte数组
     * @return
     * @throws IOException
     * @throws Exception
     */
    public static String decrypt(String data, String key) throws IOException,
            Exception {
        if (data == null)
            return null;
        BASE64Decoder decoder = new BASE64Decoder();
        byte[] buf = decoder.decodeBuffer(data);
        byte[] bt = decrypt(buf,key.getBytes());
        return new String(bt);
    }
 
    /**
     * Description 根据键值进行加密
     * @param data
     * @param key  加密键byte数组
     * @return
     * @throws Exception
     */
    private static byte[] encrypt(byte[] data, byte[] key) throws Exception {
        // 生成一个可信任的随机数源
        SecureRandom sr = new SecureRandom();
 
        // 从原始密钥数据创建DESKeySpec对象
        DESKeySpec dks = new DESKeySpec(key);
 
        // 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
        SecretKey securekey = keyFactory.generateSecret(dks);
 
        // Cipher对象实际完成加密操作
        Cipher cipher = Cipher.getInstance(DES);
 
        // 用密钥初始化Cipher对象
        cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);
 
        return cipher.doFinal(data);
    }
     
     
    /**
     * Description 根据键值进行解密
     * @param data
     * @param key  加密键byte数组
     * @return
     * @throws Exception
     */
    private static byte[] decrypt(byte[] data, byte[] key) throws Exception {
        // 生成一个可信任的随机数源
        SecureRandom sr = new SecureRandom();
 
        // 从原始密钥数据创建DESKeySpec对象
        DESKeySpec dks = new DESKeySpec(key);
 
        // 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
        SecretKey securekey = keyFactory.generateSecret(dks);
 
        // Cipher对象实际完成解密操作
        Cipher cipher = Cipher.getInstance(DES);
 
        // 用密钥初始化Cipher对象
        cipher.init(Cipher.DECRYPT_MODE, securekey, sr);
 
        return cipher.doFinal(data);
    }
}